Spark-plug construction.



J. w. MEAKER.y SPARK PLUG CONSTRUCTION. APPLICATION FILED jULY I9., 1913.

Patented Aug. 10, 1915 ,UL v

III .b

M www M@ www JOHN W. MEAKER, OF DETROIT, MICHIGAN.

SPARK-PLUG CONSTRUCTION.

1,149,388. Spcification 0f Letters Patent Patented Aug. i0, i915.

Application led July 19, 1913. Serial No. 780,019. 4

-T all @hom t may conc-em.' body. Preferably the stem is held at its I Be 1t known that I, JOHN W. MEAKER, a upper end by a suitably arranged head 14 citizen of the United States of America, rewith a spring member 15 bearing against a siding at Detroit, in the" county of Wayne washer 16 and the countersunk end of the 60 5 and State of Michigan, have invented cerhead, the spring permitting expansion and tain new and useful Improvements in Sparkcontraction of the members. As a matter Plug Construction, of which the following is of good mechanical construction the polygoa specification, reference being had therein nal bore of the member 3 may be formed as to the accompanying drawings. described in my co-pending application Se- 65 This`invention relates to spark plugs and rial Number 777,742 'wherein a screwthread to an arrangement thereof that'not only simis first formed in the wall and then a broach plifies the construction -but also assists in forced through that cuts away a part of the preventing the lodgment of moisture in the projecting thread.

sparking terminals. In the modification shown in Figs. 3, L 70 i The invention consists in the matters hereand 5 a stem 17 has a depending conical inafter set forth and particularly pointed head 18 that has cooperative relation with out in the appended claims. suitable inturned terminals 19 formed or ln the drawings, Figure 1 is a view parsecured on the bushing 3. As indicated lin tially in elevationl and partially broken Fig. 5, the conical head on the stem is in co 75 20 away and in section of one form of spark operative relation to the vertical thin edges l plug that embodies features of the inven- 21 of the inturned and upright terminals 19 tion; Fig. 2 is a plan view of the lower end on-the nipple.

thereof; Fig. 3 is a view, partially in eleva- This construction provides a light and tion and partially broken away and in s'ecdurable spark plug that is cheaply constructs0 Q 25* tion of a'slight modification of the device; edof stock material and that has a body of Fig. 4 is a plan viewof the lower end of the suliicient diameter to prevent breakage, a modicatio'n; and Fig.. 5 is a View in detail common defect in spark plugs ofthe usual of the modification. type owing' to .the material of whichv the Referring to the drawings, a body 1V of body is usually made. $5 suitable insulating material vhas a flange 2 A further feature is the disposition of the intermediate itsV ends and a central axial depending outwardly flared points of the aperture that is preferably counterbored at stem, terminal or head whereby moisture the upper end and is likewise enlarged at that may collect on the plug does not con S5 the lower end. An exteriorly screw-threadcentrateat the point and does not tend to 90. ed nipple 3 has a polygonal bore inwhich bridge the s ark gaps and thereby render the body 1 is supported, preferably ona colthe plug use ess. lar 4, an exterior bushing 5 clamping the A Obviously, changes in the details of con- I v parts in position. Preferablyy tite exterior struction may be made without departing., M bushing is made of a polygonalstock bar from the spirit of my invention and 1 do not 95 with a lower seating flange 6 turned up on care to limit myself toany particular form. its lower end and bent outwardly so that or arrangement of parts. the flange has the necessary external diame What I claim is ter. At the upper end an inner annular 1. A spark plug comprising an exteriorly flange 7. bears against a suitable packing screwthreaded nipple, a body of insulating washer 8 that is interposed between the material therein secured by a central Bange flange of the body and the bushing flange 7. on the upper end thereof, a bushing screw- A stem 9 that passes through the central threaded over the nipple and provided` with aperture ofthe body and carries at itslower an internal flange at its upper end that ico 5o yend a suitably disposed terminal 10 that is clamps the body flange against the nipple ,m5

in coperative relation to a pair of dependand with 'a lower flange that is outturned to ing lugs 11 formed-by cutting away a p'ory f form,a shoulder, depending sparkingtermitionof the bushing 8. Preferably the terminals on the nipple having sharply definednal is in the form of an inwardly .concave'df sparking edges, a stem in the bodyv and a plate with projections 12 thereon that may terminal headonthe. stem that forms spark- 1w be brought into the Vrequired distancefrornl gaps with lthe inpple terminal having upthe lugs 11 by rotation ofthe steml inthe. wardly divergent limiting edges.

2. A spark plug comprising an exterior nipple, a body of insulating material inserted in the nipple, an enlarged central portion'oi" the booy forming a shoulder supported by the niiiple, a bushing serewthreaded over the nipple and adapted to hold the enlarged central portion thereof to seat, depending sparking terminals on the nipple having sharply defined edges substantially parallel 10 to the body axis, an axial stem in the body,

and a terminal head on the stem that tapers upwardly and forms divergent spark gaps with the edges of the nipple terminals.

In testimony whereof I aiiix my signature in presence of two Witnesses.

JOHN XV. MEAKER.

Witnesses:

ANNA M. Donn, C. R. BTICKNEY. 

